Healthy & Beautiful Gardens – Disease in the garden

Hello, fellow gardeners! I was thinking what I might write about this week, realizing I’ve covered a lot of topics in the past year that I’ve been writing. Although I’ve written on “Pests and Diseases” previously, I realized I hadn’t really had enough space to go into disease much at all, so I decided this was a very important topic to address here this week due to this warm humid weather we’re currently experiencing.

Diseases are quite varied in their symptoms and certain plants are more prone to them than others. Plants are similar to humans, in that if they are not healthy to begin with, they’re usually more prone to getting sick. So, first off, make sure your plants are not suffering due to heat, lack of water, overwatering, lack of sun, too much sun, lack of good soil (compost) or lack of nutrients such as fertilizer. That will typically account for most of your problems.

If you think you’ve provided for your plant as well as you can and you’re still seeing problems, lets discuss a few of those here now. Some of the major issues I see typically involve fungus.

One of those is mildew, a powdery whitish film on plant. A form of mildew that’s common is called “Downy Mildew”, or “Black Spot.” It looks just like what it’s called and is typically found on roses.

“Rust” is another fungus that loves roses, snapdragons, and several other plants. There are also diseases called “blights”, “cankers”, “galls”, “rots”, and “wilts” – these are spread by bacteria, fungus, or viruses, either by host insects, wind, or soil. Typically warm and moist conditions cause the major fungal diseases to flourish. They can infect everything from your fruits and veggies to pine trees and lawns.

First and foremost, especially with your fruits and veggies, I suggest trying to purchase “resistant” varieties. Tomatoes are especially prone to many diseases and there are some great varieties out there that are resistant to the major wilts, blights, and fungal diseases you might encounter.

If a plant is resistant to certain kinds of fungus, it will state on the label what its resistant to. If the label says “VFNT” that means its resistant to verticillium wilt, fusarium wilt, tobacco mosaic virus and root knot nematodes.

You don’t want to use chemicals on your edibles, so what can you do? I spray with “Neem oil”. I mix 1 tablespoon to a quart of warm water. A teaspoon of mild soap can be added to the mixture also. This works great on many fungal diseases.

Sulfur is another great mineral to have handy, as it helps knock out several fungal diseases and can be used the same as copper sulfate. Copper sulfate is what I recommend on fruit trees for scab and peach leaf curl. Typically you want to spray the plant when its dormant, but copper sulfate can be used even after the trees are leafed out safely. Always follow label directions of course.

I also have used Copper sulfate on lawns instead of toxic chemicals when fungal diseases are present. “Brown Spot” is very prevalent around here and people keep watering their lawns thinking they are dying, but the reality is the fungus is doing that and the more you water, the worse your lawn looks. The solution is to spray the lawn with fungicide, or use a copper sulfate “soil drench”.

There are several other great organic methods of helping eradicating diseases. A good natural solution is baking soda, about 3 tablespoons, and liquid castile soap, about 1 tablespoon to a gallon of water. This works great on plants, but you have to cover all the leaves and stems carefully. Don’t spray the plant with the hose or sprinklers for a couple days or you’ll wash the solution off.

I also mix up some Neem oil solution and pour into the ground around the plant, as many diseases are generated below ground. Make sure when you’re using old pots with new plants to scrub them out thoroughly; use a little bleach to make sure they’re not carrying any disease spores still.

Many insects are disease carriers also, but make sure they’re not beneficial insects before you go killing them. Grasshoppers can carry diseases around, so I let my cat take care of those – keeps her busy for a while and prevents them from chewing up my plants!

Top Six suggestions from me on diseases are:

1. Be sure to plant disease-resistant varieties of plants.

2. Healthy plants, good soil, and good compost can all mitigate incidences of disease.

3. Make sure your plants have good air circulation, as this can also help prevent disease.

4. Always disinfect pruners after pruning plants to prevent the spread of fungi and bacteria.

5. Remove all diseased plants and their roots from the garden and do not compost them. Instead, throw them in the trash.

6. Manage and remove insects (aphids, spider mites, etc.) from plants regularly as needed – blast ‘em off with soapy water.

Hope I’ve addressed an issue that may help you in your garden at this time. If not, feel free to contact me. As always, I’m available for consultations and landscape design work.

Linda McDonald

Unique Landscape Designs

[email protected]


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